Question

The conditions given below are in the context of observing Tyndall effect in colloidal solutions:

(A) The diameter of the colloidal particles is comparable to the wavelength of light used.
(B) The diameter of the colloidal particles is much smaller than the wavelength of light used.
(C) The diameter of the colloidal particles is much larger than the wavelength of light used.
(D) The refractive indices of the dispersed phase and the dispersion medium are comparable
(E) The dispersed phase has a very different refractive index from the dispersion medium.

Choose the most appropriate conditions from the options given below.

• A. $\text{(B) and (E) only}$
  
• B. $\text{(C) and (D) only}$
• C. $\text{(A) and (E) only}$
• D. $\text{(A) and (D) only}$

Answer 1

The correct option is C $\text{(A) and (E) only}$

Tyndall effect:
If a strong beam of ​light is passed​ through a colloidal sols placed in dark place,​ path of the beam ​gets illuminated. This effect is called Tyndall effect.

This effect arises due to scattering of light by colloidal​ particles in all directions. Thus, scattering of light illuminates the path of beam in the colloidal dispersion​.

Condition for Tyndall effect:
1. The diameter of ​dispersed particles​ should not be much smaller than​ the wavelength of light.
2. The refractive indices of ​dispersed phase and dispersion medium​ should differ greatly in ​the magnitude​.

Hence, option (d) is correct.